. >> reporter: president obama was notified in minutes and while he was not ready to use the word "terrorist" he made this vow. >> we will find out who did this we'll find out why they did this. any responsible individuals, any responsible groups will feel the full weight of justice. make no mistake. we will get to the bottom of this. >> reporter: but new york congressman peter king is more willing to point firngers. >> obviously it's nothing give net yet but it has all the earmarks of an al qaeda attack. it reminds me of what happened in times square in 2010. it could end up being someone else but it has all the indicators of being an al qaeda or al qaeda affiliated attack. >> reporter: for rebecca roach and all the runners who ran with full hearts and their loved ones who cheered them on it's so incomprehensible and so wrong. >> i just think it's horrendous. why? i don't understand. i can't find reason in it. >> reporter: so it was a day of he heartbreak here in boston and of heroism. bruce mendelson who is an army veteran was on the scene and responded. you were right at the finish line?